JPS629970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current-limiting circuit breaker having a current-limiting action.

BACKGROUND OF THE INVENTION Circuit breakers are widely used to protect power distribution systems from overload currents, fault currents, and short circuit currents. The capacity of power supply sources has increased in recent years,
Accordingly, there is an increasing demand for circuit breakers that have a large breaking capacity and can withstand large fault currents and short circuit currents until they are completely interrupted. Traditionally, protection against large overcurrents such as those described above has been provided by current limiting fuses having sufficiently fast response times so that the circuit breaker does not experience fault peaks.

Recently, circuit breakers with current limiting function have appeared and are increasingly being used in place of current limiting fuses. This is because such current limiting circuit breakers do not need to be replaced after responding to an abnormal current; they simply need to be reset. The main part of such current-limiting circuit breakers is that the voltage of the arc that develops between the opened contacts causes the current to flow through the circuit breaker before the arc is completely extinguished and the current is completely interrupted. A fast operating mechanism configured to respond quickly enough to open the contacts of the circuit breaker the faster it rises to effectively limit the rate of rise.

[Problems to be solved by the invention] Of course, in order to move the contact at the current-limiting speed,
Forces that impede this movement should be minimized. However, in order to maintain sufficient contact pressure between the closed contacts during normal current flow to minimize the electrical resistance between the contacts and therefore the electrical resistance, the force required to open the contacts must be applied in the opposite direction. This is difficult because it requires a large amount of force. Additionally, as is well known in the art, the electromagnetic forces tending to open normally closed contacts increase as the continuous current rating of the circuit breaker increases. Therefore, the higher the current rating of the circuit breaker, the greater the contact pressure required to keep the joule heating between the contacts within acceptable limits. Furthermore, since the means for generating contact pressure is typically a spring that stretches or contracts during contact opening, the resistance of the spring to rapid contact acceleration may even increase as the contacts are opened, resulting in overcurrent in the circuit breaker. This further impairs the effective current limiting performance.

[Object of the Invention] The object of the present invention is to satisfy the above two contradictory demands, to obtain a strong contact pressure generating force in some cases, and to minimize the contact closing force in other cases. is to obtain a current circuit breaker.

[Structure of the invention] In view of this objective, the present invention provides a cooperating contact point 1.
6, 18; a conductor device 16-22, 32-40 connected to the contact and allowing the contact to be electrically connected in series to an external circuit to be protected; a contact arm support device 58; The device has one of the contacts near one end thereof, and is configured to receive a contact opening action that generates an electromagnetic force when an overcurrent of a predetermined value or more flows through the conductor device.
the contact arm support device has a movable contact arm, and the contact arm support device has two movable contact arms together with the contact arm, which correspond to the contact open position and the contact closed position, respectively;
supported for rotation between two positions;
The contact arm is (a) attached to a contact arm support device such that the contact arm can be rotated from a contact closed position to a contact open position solely by the action of electromagnetic force independently of the contact arm support device; (b) the contact arm support device; has a latching surface 86 at the other end of the arm, and a reaction surface 74 adjacent the latching surface; and (c) is combined with a spring-biased latching pin 70, the latching pin cooperating with the reaction surface and the latching surface. when the contact arm is in its contact closed position, it is spring biased against the reaction surface in the direction of contact pressure generation, and when the contact arm is moved from the contact closed position to the contact open position, the contact arm support device There are current-limiting circuit breakers in which a spring-biased latch pin is guided out of the reaction surface when being moved independently by the action of electromagnetic forces.

This arrangement utilizes a single member, a spring-biased latch pin, to provide strong contact pressure and prevent bounce or re-closing of the contact arm immediately following current-limiting action due to electromagnetic forces. Additionally, by using a spring-biased latch pin that disengages from the reaction surface of the contact arm when the contact arm is moved by electromagnetic forces as described above, the contact pressure generating force resists movement of the contact arm toward the open position. is substantially eliminated from the contact arm, and there is little resistance to the rapid acceleration of the contact arm from the closed position to the open position. Therefore, the current limiting performance of the circuit breaker is essentially not hampered by the need to provide adequate contact pressure during normal operation.

[Example] Current-limiting circuit breaker 10 of the present invention shown in FIG.
consists of a molded insulating housing 12 and a molded insulating cover 14 combined therewith.
It is equipped with Separable upper and lower contacts 1
6 and 18 are rotatable upper and lower contact arms 2
It is attached to the end of 0,22. Handle 2
6, the movement of the contact arm 20 is controlled by an operating mechanism 24 that can be manually operated. With normal current flowing through contacts 16 and 18, the automatic opening operation at normal overload currents is determined by trip unit 30.
This is accomplished by a releasable member or latch cradle 28 held by a latch member 29 attached to the cradle. This trip unit 30 is
It may have a conventional thermal, magnetic or shunt trip mechanism and will not be described in detail here. Low to moderate overload currents are
The latch member 29 moves as sensed by the trip unit 30, releasing the latch cradle 28 and pivoting the contact arm 20 upwardly.

Terminals 32 and 34 are provided for connecting the circuit to be protected and the circuit breaker 10 in series. terminal 3
2 and 34 are connected to conductors 36 and 38.
The contact arm 22 is disclosed in Japanese Patent Application No. 132521 (1983)
No. 53840) It is connected to the conductor 36 by a hinge-shaped clinch type contact portion 37 as described in the publication. An electrically conductive shunt 40 is connected between the upper contact arm 20 and the conductor 36. When the circuit breaker 10 is in the closed position as shown in FIG.
8, a circuit is formed through the contact 16, the contact arm 20, the shunt 40 and the conductor 38 to the terminal 34;
In this sense, these parts are conductor devices. A magnetic drive or slot motor 42 assists in the rapid separation of the articulation arms 20, 22 during current limiting action, as will be explained in more detail below.
An arc extinguishing plate 43 is provided to promote extinguishing of the arc generated by the opening of the contacts 16 and 18.

The operating mechanism 24 is shown in detail in FIG. A frame with side plates 44 is secured to the housing 12 by screws 45. A latch cradle 28 is pivotally mounted to the side plate 44 by a pin 46. Between the pivot pin 48 of the contact arm 20 and the latch cradle 28, there is a
Upper toggle link 50 and lower toggle link 5
A toggle device consisting of two is connected by a shaft. The two toggle links 50, 52 are connected by a toggle knee pin 54 to which an operating spring 5 is connected.
6 is attached at one end, and the other end of this spring is attached to the handle 26.

A carriage pivot pin 60 is attached to the side plate 44.
U-shaped carriage or contact arm support device 5
8 is rotatably attached. The pivot pin 48 of the upper contact arm 20 described above is attached to this contact arm support device 58. Therefore, during normal operation (non-current limiting operation), the contact arm 20 rotates about the carriage pivot pin 60, integrally with the U-shaped contact arm support device 58. Since the lower toggle link 52 is connected to the contact arm pivot pin 48 through the contact arm support device 58, collapse and expansion of the toggle device consisting of the toggle links 50, 52 will cause the contact arm support device to collapse and extend. 58 rotates about a carriage pivot pin 60. The movement of the contact arm support device 58 is restricted by engagement between the long hole 62 provided in the side plate 44 and the end of the pivot pin 48 inserted therein. A crossbar 64 fixed to the contact arm support device 58 extends to corresponding carriages of pole units (not shown) on both sides.

A relatively weak tension spring 66 is connected between a pin 67 (attached to the contact arm 20) and the carriage pivot pin 60 on each side of the contact arm 20. A relatively strong tension spring 68 is also connected between the movable latch pin 70, which is received in the arcuate elongated hole 72 in the side plate 44 of the frame, and the contact arm support device 58. . When the circuit breaker is in the closed position shown in FIG. 2, the latch pin 70 is urged against the reaction surface 74 of the contact arm 20 by the action of the strong tension spring 68. In this manner, the springs 66, 68 are stretched to create tension, and the contact arm 20 is in equilibrium with the contact pressure and the reaction force resulting from the springs 66, 68 and the contact arm support device 58 acting on the contact arm pivot pin 48. and is in a floating state.

The position of the lower contact arm 22 is such that the compression spring 78 and
Defined by a spring biased shutter assembly 76 consisting of a spring receiver 80 and a limit pin 82. Compression spring 78 will counteract the contact force from upper contact arm 20 acting on contact arm 22 .

When the circuit breaker is placed in the normal open position by manual operation of the handle 26, the mechanisms are in the positions shown in FIG. As can be seen from the figure, the upper and lower toggle links 50, 52 are broken, allowing clockwise rotation about the pin 60 of the contact arm support device 58. The upper contact arm 20 is connected to the contact arm support device 58
The contact points 16 and 18 are separated by rotating together with the contact point 16 and 18. A weak tension spring 66 connects the upper contact arm 20
and pull it up to connect the contact arm support device 5.
8 is pressed against the pick-up piece 84 attached to the pick-up piece 84. At this time, latch pin 70
(The force of the spring acts through this pin when the circuit breaker is in the closed position) is pressed against the upper end of slot 72 and is not in contact with contact arm 20, so the force from strong spring 68 is , does not act on the contact arm 20. The lower contact arm 22 is raised slightly from the closed position of FIG. 2 to the position of FIG. 3 by the action of the compression spring 78. The upper limit of the range of movement of lower contact arm 22 is determined by the action of limit pin 82 on the side of slot motor 42.

Under low to moderate overload conditions, trip unit 30 operates to move latch member 29 and release cradle 28. The circuit breaker is then in the position shown in FIG. 4, and the cradle 28 is rotated counterclockwise about the pin 46 from the position shown in FIG. 2 by the action of the operating spring 56. For this reason, the toggle device consisting of toggle links 50 and 52 collapses,
The contact arm support device 58 is now able to rotate clockwise about the carriage pivot pin 60. The handle 26 is moved to the central trip position as shown in FIG. 4, and the crossbar 64, along with the contact arm support 58, rotates to open the other pole of the circuit breaker. All other parts of the circuit breaker are in the same position as in the normal open position of FIG.

When a large overload current flows through the circuit breaker 10 in the closed position shown in FIG. 2, a strong electromagnetic force is generated and this electromagnetic force acts on the contact arms 20 and 22. They rotate in opposite directions to try to separate the contacts 16 and 18. Furthermore, the current flows through the conductor 36 and the contact arm 22, inducing magnetic flux in the slot motor 42, causing the contact arm 22 to flow.
The contact opening force is further increased by pulling the contact point toward the bottom of the slot. Since the cradle 28 and toggle links 50, 52 are not immediately affected, they remain in the position shown in FIG. 2 along with the contact arm support 58. Therefore, the electromagnetic force acting on the upper contact arm 20 causes the contact arm 20 to pivot about the pivot pin 48. At the beginning of this rotation, the reaction surface 74 engages the latch pin 70.
moves the latch pin 70 downwardly within the elongated hole 72. Initially, latch pin 70 moves downwardly within slot 72 against the action of spring 68. Therefore, the force of spring 68 is applied to contact arm 20
increases in proportion to the movement of the current, and attempts to resist the current limiting action by resisting the electromagnetic force caused by the overload current. However, the elongated hole 72 connects the latch pin 70 to the contact arm 2.
The reaction surface 74 disengages from the latch pin 70 at about midway through the movement of the contact arm 20 (i.e., before the spring 68 is significantly stretched) and the released spring 68 The force pulls the latch pin 70 up to the top of the slot 72. Of course, the position at which the contact arm 20 and the latch pin 70 are separated can be adjusted by adjusting the shape of the elongated hole 72.

As shown in FIG.
2, this pin engages the latching surface 86 of the contact arm 20. Therefore, even though the force of the weak tension spring 66 attempts to rotate the contact arm 20 counterclockwise back to the closed position, the latch remains closed.
The latching action of pin 70 prevents this from happening.

As contact arms 20 and 22 move to the current limiting position of FIG. 5, an arc is generated between the two contacts 16 and 18. Although this arc is pressed against the arc extinguishing plate 43 and is extinguished fairly quickly, the current continues to flow long enough for the trip unit 30 to operate and release the cradle 28. Release of cradle 28 allows rotation of contact arm support 58, causing latching surface 86 of contact arm 20 to move along and eventually release from latch pin 70. When the contact arm support 58 is rotated enough to release the latch face 86 from the latch pin 70, the weak tension spring 66 tends to rotate the contact arm 20 counterclockwise. However, such rotation of contact arm 20 is limited by pick-up block 84 which engages latch surface 86. At this time, the circuit breaker is in the position shown in FIG.

[Effects of the Invention] As is clear from the above description, the magnitude of the contact contact pressure in the normal closed position can be set by appropriately selecting the characteristics of the spring 68.
This force can be removed from the contact arm 20 at any point during the current limiting operation of the contact arm 20 by appropriately selecting the location and shape of the slot 72. Acceleration of the contact arm 20 is resisted by allowing the contact arm 20 to release from this contact contact pressure early, before the spring 68 has fully extended to substantially impede movement of the contact arm. The force required to do so can be minimized. This not only increases the current limiting effect of the circuit breaker, but also reduces the mechanical force applied to the contact arm during current limiting operation.
Since a strong spring that does not need to be stretched significantly is used, the stress acting on this spring is also reduced.
Increased spring service life and reliability. Additionally, the operating mechanism is simple because a common spring is used to provide contact pressure on the contacts in the closed position and to provide latching force during current limiting operation. in this way,
According to the present invention, a current limiting circuit breaker with an excellent latch release mechanism, high performance, and low cost has been obtained.

[Brief explanation of the drawing]

FIG. 1 is a side view of the current limiting circuit breaker of the present invention, FIG. 2 is a sectional view of the contact arm and operating mechanism of the current limiting circuit breaker of FIG. 1 with the contacts in the closed position, and FIG. 2 is a view similar to FIG. 2 with the contacts and operating mechanism in the normally closed position, FIG. 4 is a view similar to FIG. 2 showing the contacts and the operating mechanism in the tripped position, and FIG. FIG. 2 is a view similar to FIG. 2 showing the contacts and operating mechanism in the current-limiting position; 16, 18...Contact, 20...Contact arm, 16-
22, 32-40... Conductor device, 58... Contact arm support device, 70... Latch pin, 72... Long hole,
74...reaction surface, 86...latch surface.

Claims (1)

[Scope of Claims] 1. Comprising a cooperating contact, a conductor device connected to the contact and allowing the contact to be electrically connected in series to an external circuit to be protected, and a contact arm support device. , wherein the conductor device has one of the contacts near one end thereof, and is configured to receive a contact opening operation that generates an electromagnetic force when an overcurrent of a predetermined value or more flows through the conductor device. the contact arm support device has a movable contact arm;
The contact arm support device is supported so as to be rotatable together with the contact arm between two positions of the contact arm corresponding to a contact open position and a contact closed position, and the contact arm is configured to: (a) (b) the contact arm is attached to the contact arm support device such that the contact arm can be rotated from the contact closed position to the contact open position solely by the action of the electromagnetic force, independently of the contact arm support device; a latching surface at the other end and a reaction surface adjacent the latching surface; and (c) combined with a spring biased latching pin;
The latch pin is operable to cooperate with the reaction surface and the latching surface and is spring-biased relative to the reaction surface in the direction of contact pressure generation when the contact arm is in its contact closed position; The spring-biased latch pin is guided out of the reaction surface when being moved from the contact closed position toward the contact open position by the action of the electromagnetic force independently of the contact arm support device. Current limiting circuit breaker. 2. The current limiting circuit according to claim 1, wherein the pivot of the contact arm support device, the pivot of the movable contact arm on the contact arm support device, and the long axis of the latch pin are parallel to each other and spaced apart. circuit breaker. 3. The contact arm support device is rotatably supported by a frame, and the frame is formed with a pair of guide slots in guide engagement with both ends of the latch pin. Current-limiting circuit breaker according to item 2. 4. The guide slot directs the movement of the spring-biased latch pin by the spring biasing action, while the contact arm support is moving towards the contact open position, the latch pin is directed towards the reaction surface or the latch. 4. The current limiting circuit breaker according to claim 3, which limits the current to the extent that it deviates from the plane. 5. The current limiting device according to claim 3 or 4, wherein the frame has a stop device that prevents the contact arm support device from rotating beyond the open position and the closed position. circuit breaker. 6. A patent claim in which the stop device is a pair of elongated holes, and the contact arm is pivotally supported on the contact arm support device by a pivot pin having opposite ends freely engaged in the respective elongated holes. Current-limiting circuit breaker according to item 5. 7. The movable contact arm includes a return spring device that biases the contact arm in a contact pressure generation direction, and the contact arm support device is configured to bias the contact arm in a contact pressure generation direction, and the contact arm support device is configured to bias the contact arm in a contact pressure generating direction, and the contact arm support device a device for limiting movement of the contact arm relative to the contact arm support device by action of the device, the spring biased latch pin engaging the reaction surface and being applied to the contact arm; 7. The current limiting circuit breaker according to claim 1, wherein the contact pressure is greater than the contact pressure generating force applied to the contact arm by the return spring device.